Wernicke's encephalopathy: is diffusion-weighted MRI useful?

We present the clinical and magnetic resonance imaging (MRI) findings of five patients with acute Wernicke's encephalopathy. T2-weighted and fluid-attenuated inversion recovery (FLAIR) images demonstrated symmetrical hyperintense lesions within the dorsomedial thalami, periaqueductal white matter, and the tectum of the midbrain. None of the lesions enhanced with gadolinium. In addition to conventional MRI sequences, we performed diffusion-weighted imaging (DWI). In all patients, DWI showed symmetrical pathologic thalamic and midbrain signal hyperintensities more distinctly than did conventional T2-weighted or FLAIR sequences. The apparent diffusion coefficient (ADC) map images showed slight signal reductions in four patients, suggesting restricted diffusion within these regions. In one patient, the signal intensity within the affected thalami was isointense with the ipsilateral basal ganglia on ADC map images. For enhanced detection of pathology, we conclude that DWI should be included in the imaging protocols of patients suspected to suffer from Wernicke's encephalopathy.     

Development of brain infarct volume as assessed by magnetic resonance imaging (MRI): follow-up of diffusion-weighted MRI lesions

PURPOSE: To investigate the development of ischemic brain lesions, as present in the acute stroke phase, by diffusion-weighted magnetic resonance imaging (DWI), and in the subacute and chronic phases until up to four months after stroke, in fluid-attenuated inversion recovery (FLAIR)- and T2-weighted (T2W) magnetic resonance (MR) images. MATERIALS AND METHODS: Twelve consecutive patients with their first middle cerebral artery (MCA) infarction were included. Lesion volumes were assessed on T2W images recorded with a turbo spin echo (TSE) and on images recorded with the FLAIR sequence on average on day 8 and after about four months. They were compared with acute lesion volumes in perfusion and DWI images taken within 24 hours of stroke onset. RESULTS: On day 8, lesion volumes in images obtained with FLAIR exceeded the acute infarct volumes in DWI. The chronic lesion volumes were almost identical in T2W and FLAIR images but significantly reduced compared with the acute DWI lesions. The lesion volumes assessed on DWI images correlated highly with the lesions in the images obtained with TSE or FLAIR, as did the lesions in the images obtained with FLAIR and TSE. The secondary lesion shrinkage was accompanied by ventricular enlargement and perilesional sulcal widening, as most clearly visible in the images obtained with FLAIR. CONCLUSION: Our results show that the acute DWI lesions are highly predictive for the infarct lesion in the chronic stage after stroke despite a dynamic lesion evolution most evident in MR images obtained with FLAIR.     

MR弥散加权成像对AICA与PICA梗死的诊断价值

目的：探讨MRI在小脑前下动脉(AICA)与小脑后下动脉(PICA)供血区梗死的诊断及鉴别诊断价值。方法：搜集临床确诊的AICA供血区梗死5例和PICA供血区梗死7例．临床表现为典型或部分的AICA综合征与PICA综合征．全部行MRI检查．包括SE、FLAIR和DWI序列。结果：MRI可以良好显示AICA和PICA供血区梗死的部位与形态．其中DWI序列具有更佳的敏感性和特异性．通过与SE／FLAIR序列的对照，有助于确定病变范围和鉴别病灶的新鲜程度。结论：MR弥散加权成像可以帮助；住确地诊断和鉴别AICA与PICA供血区梗死，为临床诊治提供依据。     

Reversible splenial abnormality in hypoglycemic encephalopathy

Introduction Lesions involving the splenium of the corpus callosum (SCC) have been rarely reported in cases of hypoglycemic brain injury. Methods We identified signal abnormalities in the SCC in three adult patients with hypoglycemic encephalopathy by using diffusion-weighted imaging (DWI) on a 1.5-T MR scanner. Repeat DWI was performed in all patients following a marked clinical improvement, and MR angiography and routine MRI were also performed. We examined each patient’s detailed medical history and blood laboratory tests in order to exclude other conditions causing similar SCC abnormalities. Results Initial DWI was performed during which each patient showed altered mental status that was attributed to profound hypoglycemia. We observed an identical pattern of DWI abnormality characterized by high signals in the SCC with apparent diffusion coefficient reductions that were reversed completely within several days following appropriate correction of hypoglycemia. T2-weighted or FLAIR images also showed no residual lesion in the SCC and MR angiography was normal in all patients. Conclusion These case reports suggest that the SCC should be added to the list of selective vulnerability to hypoglycemia and that hypoglycemia, in turn, be included in the differential diagnosis of reversible SCC abnormalities.     

Diffusion-weighted imaging in patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a severe demyelinating disease of the central nervous system due to JC polyoma virus infection of oligodendrocytes. PML develops in patients with impaired T-cell function as occurs in HIV, malignancy or immunosuppressive drugs users. Until now no imaging methods have been reported to correlate with clinical status. Diffusion-weighted imaging (DWI) is a robust MRI tool in investigating white matter architecture and diseases. The aim of our work was to assess diffusion abnormalities in focal white matter lesions in patients with PML and to correlate the lesion load measured with conventional MRI and DWI to clinical variables. We evaluated eight patients with a biopsy or laboratory-supported diagnosis of PML. All patients underwent MRI including conventional sequences (fluid attenuated inversion recovery-FLAIR) and DWI. Mean diffusivity (MD) maps were used to quantify diffusion on white matter lesions. Global lesion load was calculated by manually tracing lesions on FLAIR images, while total, central core and peripheral lesion loads were calculated by manually tracing lesions on DWI images. Lesion load obtained with the conventional or DWI-based methods were correlated with clinical variables such as disease duration, disease severity and survival. White matter focal lesions are characterized by a central core with low signal on DWI images and high MD (1.853 × 10⁻³ mm2/s), surrounded by a rim of high signal intensity on DWI and lower MD (1.1 × 10⁻³ mm2/s). The MD value of normal-appearing white matter is higher although not statistically significant (0.783 × 10⁻³ mm2/s) with respect to control subjects (0.750 × 10⁻³ mm2/s). Inter-rater correlations of global lesion load between FLAIR (3.96%) and DWI (3.43%) was excellent (ICC =0.87). Global lesion load on FLAIR and DWI correlates with disease duration and severity (respectively, p = 0.037, p = 0.0272 with Karnofsky scale and p = 0.0338 with EDSS on FLAIR images; p = 0.043, p = 0.0296 with Karnofsky scale and p = 0.0365 with EDSS on DW images). Central core lesion load on DWI correlates with disease duration and severity (respectively p = 0.043, p = 0.0103 with Karnofsky scale and p = 0.0112 with EDSS), while peripheral lesion load does not correlate with any clinical variable. The global lesion load in PML correlates with disease duration and severity. DWI images, which can distinguish within lesions a central core from a peripheral rim, reveal that a larger central core component correlates to a worsened clinical status and longer disease duration. On the other hand the peripheral rim lesion load visualized on DWI images does not correlate with clinical variables and does not achieve obtaining further prognostic information with respect to conventional imaging.     

0.5T磁共振机弥散加权像诊断急性脑梗塞

目的：分析０．５Ｔ磁共振机的弥散加权像（ＤＷＩ）对急性脑梗塞诊断的临床价值。材料与方法：计算５０例健康志愿者正常脑组织各不同部位的表观弥散系数（ＡＤＣ）值,并对急性脑梗塞发作后３～１２小时的１０名患者进行ＤＷＩ及常规Ｔ_１ＷＩ、Ｔ_２ＷＩ、ＦＬＡＩＲ及ＭＲＡ检查。结果：测得正常人额、顶、枕叶脑白质、半卵圆中心、基底节、脑干、小脑半球、脑脊液部位的ＡＤＣ平均值。对于临床患者,ＤＷＩ可明确显示急性期脑梗塞病灶,常规Ｔ_１ＷＩ、Ｔ_２ＷＩ、ＦＬＡＩＲ均不能显示或显示不清。结论：以ＤＷＩ为主,结合Ｔ_１ＷＩ、Ｔ_２ＷＩ、ＦＬＡＩＲ及ＭＲＡ序列能非常准确、可靠的诊断急性脑梗塞。     

MRI findings of Wernicke encephalopathy revisited due to hunger strike

BACKGROUND AND PURPOSE: The purpose of this study was to determine the characteristic magnetic resonance imaging (MRI) findings among a group of patients who presented with Wernicke encephalopathy (WE) due to the neurological complications of a long-term hunger strike (HS). METHODS: MRI studies also including the fluid-attenuated inversion recovery (FLAIR) sequence and diffusion-weighted imaging (DWI) of six male patients with WE aged from 25 to 38 years (mean age 31 years) were evaluated. RESULTS: In all subjects, T2-weighted sequences, FLAIR and DWI revealed a signal hyperintensity within the posteromedial thalami and surrounding the third ventricle. In particular, on coronal images, the hyperintense areas around the third ventricle showed a suggestive "double wing" configuration. We observed an increased signal on proton-density and T2-weighted images in the mamillary bodies of three patients. Four patients demonstrated additional hyperintensities within the periaqueductal region and/or the tectal plate. At least one lesion area in five of six patients demonstrated contrast enhancement. CONCLUSION: The consistent imaging findings of our study suggest that MRI is a reliable means of diagnosing WE. Acute WE is sometimes underdiagnosed, yet early diagnosis and treatment of WE is crucial in order to avoid persistent brain damage. MRI, including postcontrast T1-weighted imaging, DWI beneath standardized T2-weighted imaging, and FLAIR sequences may prove to be a valuable adjunct to clinical diagnosis and to provide additional information in acute and/or subacute WE.     

Evolution of lesions in Susac syndrome at serial MR imaging with diffusion-weighted imaging and apparent diffusion coefficient values

BACKGROUND AND PURPOSE: Susac syndrome is a rare disorder consisting of encephalopathy, hearing loss, and retinal arteriolar occlusions. The purpose of this study was to evaluate the evolution of lesions in this disease by using serial MR imaging with diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADCs). Abnormalities in the nonlesional white matter (NLWM) were also analyzed. METHODS: Serial MR and DWI findings in two patients with Susac syndrome were reviewed retrospectively. ADCs of the lesions and the NLWM were compared with values of the corresponding anatomical regions in 16 control subjects. RESULTS: T2-weighted images, DWIs, and fluid-attenuated inversion-recovery (FLAIR) images demonstrated diffuse small hyperintense lesions predominantly involving the corpus callosum, white matter, cerebral cortex, and deep gray structures. During the whole course in the two patients, 437, 295, and 113 lesions were depicted on FLAIR images, T2-weighted images, and DWIs, respectively. With the aggravation and mitigation of the clinical symptoms, the size and number of the lesions changed over time. Of 65 lesions with measured ADCs, six had restricted ADCs (5.29-6.91 x 10(-4) mm(2)/s), and 29 had elevated ADCs (8.02-13.5 x 10(-4) mm(2)/s). With disease progression, ADCs in the NLWM changed from normal to elevated; this corresponded to the diffuse signal-intensity change seen in the white matter. CONCLUSION: FLAIR imaging is the most sensitive sequence for detecting lesions of Susac syndrome. DWI is useful in demonstrating the heterogeneous nature of lesions, depicting occult abnormalities in the white matter, elucidating underlying pathologic processes, and conducting patient follow-up.     

Inter‐ and intraobserver reliability of five MRI sequences in the evaluation of the final volume of cerebral infarct

Purpose

To evaluate the reproducibility of fluid attenuated inversion recovery (FLAIR) and four other magnetic resonance imaging (MRI) sequences in the quantitative assessment of final cerebral infarct volume.

Materials and Methods

FLAIR, T1‐3D, magnetization transfer ratio (MTR)‐map, diffusion‐weighted trace (DWI)‐trace, and apparent diffusion coefficient (ADC)‐map, were acquired and measured in 33 patients 30–45 days after onset of a first‐ever ischemic stroke. The infarct area was visually detected and manually delineated two times by two readers separately after images and sequences randomization. The reliability was assessed by using an intraclass correlation coefficient (ICC) and its two‐sided 95% confidence interval (95% CI).

Results

DWI‐trace had the best reliability, with an ICC of 0.96 (95% CI = 0.93–0.98). FLAIR had an ICC of 0.86 (95% CI = 0.73–0.93), and a much higher volume. T1‐3D, MTR‐map and ADC‐map had lower reliability or excessive volume values equal to 0 in comparison to DWI‐trace.

Conclusion

DWI‐trace performed within 30th and 45th day following onset of acute ischemic stroke was the most reliable sequence for final infarct volume quantification. This sequence should be added to FLAIR evaluation to strengthen the statistical results of the pharmacological trials and reduce their variability. J. Magn. Reson. Imaging 2009;29:1280–1284. © 2009 Wiley‐Liss, Inc.     

Etiology of cortical and white matter lesions in cyclosporin-A and FK-506 neurotoxicity.

BACKGROUND AND PURPOSE: The etiology of the neurotoxicity associated with cyclosporin-A (CsA) and FK-506 treatment is not fully understood. At our institution, we noticed a distinct, abrupt change in the imaging characteristics of CsA and FK-506 neurotoxicity, which consisted of a shift in lesion morphology from a white matter abnormality to a mixed cortical and white matter pattern. The purpose of this study was to assess clinical parameters that might explain this change. METHODS: Twenty-two patients had a neurotoxic reaction and brain imaging changes while receiving CsA or FK-506. Nineteen patients received allogeneic bone marrow transplants, and three had aplastic marrow disorders. Fifty-one imaging studies (CT or MR imaging) were obtained, and lesion characteristics, locations, and time courses were evaluated along with relevant clinical data. RESULTS: Nine patients who had been conditioned for transplantation with cyclophosphamide and chemotherapy (busulfan or thiotepa) had a mixed pattern of cortical and white matter involvement (57 lesions). Isolated white matter involvement (62 lesions) developed in three nontransplant patients and 10 transplant patients conditioned with cyclophosphamide and total-body irradiation. All lesions occurred at typical brain watershed zones. Lesion enhancement was noted in two patients conditioned with chemotherapy. Initial images demonstrated characteristic lesions in 15 patients (68%). Initial images were normal in four patients (18%) and nonspecific in three patients (14%). CONCLUSION: Lesion location in CsA and FK-506 neurotoxicity may depend on the presence or type of conditioning used before bone marrow transplantation. Nontransplant patients or those conditioned with total-body irradiation develop white matter lesions, whereas those conditioned with chemotherapy develop mixed cortical and white matter lesions.     

Diffusion MR Imaging with T2-based Water Suppression (T2wsup-dMRI)

Purpose: This study proposes and assesses a new diffusion MRI (dMRI) technique to solve problems related to the quantification of parameter maps (apparent diffusion coefficient [ADC] or mean diffusivity [MD], fractional anisotropy [FA]) and misdrawing of fiber tractography (FT) due to cerebrospinal fluid (CSF)-partial volume effects (PVEs) for brain tissues by combining with the T2-based water suppression (T2wsup) technique.Methods: T2wsup–diffusion-weighted imaging (DWI) images were obtained by subtracting those images from the acquired multi-b value (b) DWI images after correcting the signal intensities of multiecho time (TE) images using long TE water signal-dominant images. Quantitative parameter maps and FT were obtained from minimum data points and were compared with those using the standard (without wsup) DWI method, and partly compared with those obtained using other alternative DWI methods of applying fluid attenuation inversion recovery (FLAIR), non-b-zero (NBZ) by theoretical or noise-added simulation and MR images.Results: In the T2wsup-dMRI method, the hyperintense artifacts due to CSF-PVEs in MRI data were dramatically suppressed even at lower b (≲ 500 s/mm²) while keeping the tissue SNR. The quantitative parameter map values became precisely close to the pure tissue values precisely even in water (CSF) PVE voxels in healthy brain tissues (T2 ≲ 100 ms). Furthermore, the fiber tracts were correctly connected, particularly at the fornix in closest contact to the CSF.Conclusion: Solving the problem of CSF-PVE in the current dMRI technique using our proposed T2wsup-dMRI technique is easy, with higher SNR than those obtained with FLAIR or NBZ methods when applying to healthy brain tissues. The proposed T2wsup–dMRI could be useful in clinical settings, although further optimization of the pulse sequence and processing techniques and clinical assessments are required, particularly for long T2 lesions.     

可逆性后部脑病综合征的CT和MRI诊断

目的 探讨可逆性后部脑病综合征(RPES)的CT和MRI特点.方法回顾性分析5例经临床随访证实的RPES患者的临床和MRI资料.结果 头颅MRI检查显示病变累及双侧枕叶4例,双侧顶叶及双侧基底节对称性受累各2例,2例单侧顶叶受累,1例伴胼胝体压部受累,1例左侧小脑受累.MRI信号呈T_1WI低信号,T_2WI高信号,FLAIR序列病灶信号明显增高,增强扫描病灶无明显强化.5例弥散加权成像随着b值的加大(0,500,1000 s/mm2),病灶高信号逐渐减低,ADC信号略增高.CT扫描病灶呈低密度影.结论 MRI表现结合临床资料,可正确诊断可逆性后部脑病综合征.     

Diffusion-weighted and fluid-attenuated inversion recovery imaging in Creutzfeldt-Jakob disease: high sensitivity and specificity for diagnosis

BACKGROUND AND PURPOSE: Abnormalities on diffusion-weighted images (DWIs) and fluid-attenuated inversion recovery (FLAIR) images are reported in Creutzfeldt-Jakob disease (CJD). To our knowledge, no large study has been conducted to determine the sensitivity and specificity of DWI and FLAIR imaging for diagnosing CJD. METHODS: Two neuroradiologists, blinded to diagnosis, retrospectively evaluated DWI and FLAIR images from 40 patients with probable or definite CJD and 53 control subjects with other forms of dementia and rated the likelihood of CJD on the basis of the imaging findings. RESULTS: DWI and FLAIR imaging was 91% sensitive, 95% specific, and 94% accurate for CJD. Interrater reliability was high (kappa = 0.93). Sensitivity was higher for DWI than FLAIR imaging. Abnormalities involved cortex and deep gray matter (striatum and/or thalamus) in 68% of patients with CJD, cortex alone in 24%, and deep gray matter alone in 5%. The most typical and specific patterns were corresponding hyperintensity on both FLAIR images and DWIs confined to the gray matter in the cortex, striatum, medial and/or posterior thalamus, or a combination of these areas. Narrow-window soft-copy review of artifact-free DWIs and FLAIR images and recognition of the normal variation in cortical signal intensity proved critical for successful differentiation of CJD from other dementias. CONCLUSION: Because specific patterns of abnormality on DWI and FLAIR images are highly sensitive and specific for CJD, these sequences should be performed whenever CJD is suspected.     

可复性后部脑病综合征的MR诊断

目的 提高对可复性后部脑病综合征(PRES)的MRI诊断及鉴别诊断的认识.资料与方法 回顾性分析8例经临床证实的PRES患者的临床及MRI表现.8例均行MRI检查,其中3例行钆喷替酸葡甲胺(Gd-DTPA)增强扫描,2例行磁共振血管造影(3D-TOF MRA)检查,1例行增强磁共振静脉成像(CE-MRV)检查,6例行扩散加权成像(DWI).结果 MRI显示病灶基本上呈双侧对称性分布,6例位于顶、枕叶皮层及皮层下,2例累及脑干.T_1WI呈等或略低信号,T_2WI及液体衰减反转恢复(FLAIR)呈高信号,注射Gd-DTPA后无明显异常对比强化,MRA未见明显异常,DWI显示病变扩散受限呈高信号,ADC图呈高信号或为正常.7例经对症处理后多次复查示所有病灶几乎完全吸收消失,临床症状好转;1例因多系统衰竭死亡.结论 MRI对PRES的病变范围显示清楚,具有一定的特征性,多种MR检查方法并结合治疗后复查可以明确该病的诊断.     

The approximate planimetric method: a simple,rapid and reliable method for estimation of lesion size in acute ischemic stroke

Magnetic resonance imaging is increasingly used in stroke trials for early diagnosis and follow-up of lesion size. Since volumetric measurement remains a laborious and time-consuming task, a rapid and reliable method for the assessment of lesion size has been developed and validated in diffusion weighted imaging (DWI) and fluid attenuated inversion recovery (FLAIR) sequences. These were serially obtained in 40 patients less than 8 h after the onset of symptoms of a middle cerebral artery territory stroke (day 1), as well as on days 3 and 18. For each of 16 (DWI) or 20 (FLAIR) transverse sections obtained on each occasion, lesion size was estimated as a percentage of the total hemisphere. Percentage values from all sections were summed up and expressed as arbitrary units. Results obtained using this approximate planimetric method (APM) were compared with those from a standard volumetric approach. Lesion volumes as determined by both methods were highly correlated (DWI: r = 0.966, FLAIR: r = 0.979, p < 0.001). To conclude, the APM is simple, rapid and reliable for the estimation of lesion size in acute ischemic stroke. It can be recommended for broader application in clinical trials.     

Cerebrospinal fluid-suppressed high-resolution diffusion imaging of human brain

A cerebrospinal fluid (CSF)-suppressed flow-attenuated inversion recovery (FLAIR) double-shot diffusion echo-planar imaging (EPI) sequence was developed and used, along with a non-CSF-suppressed version of the sequence, to determine the extent of the contribution of CSF partial-volume averaging to the apparent diffusion coefficients (ADCs) of normal human brain in vivo. Regional analysis indicates that cortical gray matter and parenchymal tissues bordering the ventricles are most affected by CSF contamination, leading to elevated ADC values. Only slight differences in gray- and white-matter average ADCs were detected after CSF suppression. The human brain average ADCs calculated from high-resolution CSF-sup-pressed diffusion-weighted images in these studies are similar to those reported in animals. FLAIR diffusion sequences remove CSF as a source of error in ADC determination and ischemic lesion discrimination in diffusion-weighted images (DWI) and ADC maps.     

磁敏感加权成像在新生儿缺氧缺血性脑病中的应用

目的：探讨磁敏感加权成像（SWI）在新生儿缺氧缺血性脑病中的应用价值。方法：对临床拟诊缺氧缺血性脑病（HIE）的105例新生儿行头颅横断面液体衰减反转恢复序列（FLAIR）、快速自旋回波（FSE）、扩散加权图像（DWI）及磁敏感加权成像（SWI）,重点观察SWI对新生儿HIE出血性病灶检出的敏感性。结果：SWI能很好显示HIE伴发的出血灶,尤其是在室管膜生发基质以及脑室内出血的显示率明显高于其他扫描序列。结论：SWI对新生儿HIE伴发的出血,尤其慢性期、微小出血灶以及静脉病变的显示优势明显,而这些信息直接与患儿的预后密切相关,因此它是常规扫描序列的重要补充,有必要将SWI列为HIE的扫描序列。     

流行性乙型脑炎的MRI诊断及临床意义

目的 探讨流行性乙型脑炎(乙脑)的MRI影像表现和临床应用价值.资料与方法 经临床血清学检测确诊的14例乙脑患者.全部行MRI扫描,扫描序列包括:T1-液体衰减反转恢复序列(FLAIR)、T2WI、T2-FLAIR和扩散加权成像(DWI).分析病灶累及部位和各序列的MRI信号特征.结果 病灶单独累及丘脑者3例,累及双侧丘脑同时伴有单个或多个其他部位受累10例,其中大脑脚、基底节、大脑皮层及小脑齿状核受累分别为6、4、2、1例.1例为右侧额叶广泛受累.病灶在T1-FLAIR多数呈低信号,在T2WI呈高信号.DWI上高信号7例,等信号4例,低信号3例.14例在T2-FLAIR上全部呈高信号.2例病灶中合并有出血灶.结论 乙脑可以累及多个部位,但以双侧丘脑损害为特征性表现.T2-FLAIR和DWI对乙脑诊断及治疗中随访观察有很高的诊断价值,MRI可作为乙脑的首选影像诊断手段.     

Creutzfeldt-Jakob disease: comparative analysis of MR imaging sequences

BACKGROUND AND PURPOSE: MR imaging has played an increasingly important role in the diagnosis of Creutzfeldt-Jakob disease (CJD) since basal ganglia abnormalities on T2-weighted images have been described; thus, the aim of our study was to compare the value of different MR images in the diagnosis of CJD. METHODS: One hundred fifty-seven patients with CJD underwent MR imaging examinations. Ninety-two patients were neuropathologically confirmed, and 65 were clinically classified as having CJD through the CJD Surveillance Unit (probability of 95%). There was no standardized MR imaging protocol; thus, the examinations included 143 T2-weighted, 43 proton attenuation (PD)-weighted, 84 fluid-attenuated inversion recovery (FLAIR), and 44 diffusion-weighted images (DWI). The MR images were reviewed for pathologic changes of the basal ganglia, thalamus, and cerebral cortex. RESULTS: Cortical abnormalities were present in 70 patients (45%) and were visible in 80% (35/44) of all available DWI examinations. The basal ganglia were affected in 94 patients (60%), in particular in the caudate nucleus; the most sensitive sequences were DWI (64%) and PD-weighted (63%). A thalamic involvement was more frequently diagnosed on PD-weighted images (19%) and DWI (14%) than on FLAIR or T2-weighted images. CONCLUSION: PD-weighted images and DWI showed better results in the diagnosis of signal intensity changes in the basal ganglia compared with T2-weighted or FLAIR images; however, in the diagnosis of cortical changes, DWI was clearly superior. Our data suggest that DWI is the most sensitive MR imaging technique in the diagnosis of CJD.     

Diffusion-weighted imaging for the evaluation of diffuse axonal injury in closed head injury

PURPOSE: The purpose of this work was to compare diffusion-weighted imaging (DWI) with conventional MRI in the detection of shearing injuries in acute closed head injuries. METHOD: Twenty-five patients (19 male, 6 female) were examined within 48 h of trauma. Conventional MRI included T2-weighted fast spin echo, fluid-attenuated inversion recovery (FLAIR), and T2*-weighted gradient echo sequences. Full tensor DWI with calculation of apparent diffusion coefficient (ADC) maps was also performed. Lesions were identified and compared on all sequences. RESULTS: Four hundred twenty-seven lesions were counted by the combined use of all sequences. DWI identified 70 lesions not seen on conventional MRI. DWI identified 310 shearing injuries, followed by T2/FLAIR (n = 248) and T2* (n = 202). The majority of DWI-positive lesions showed decreased diffusion (65%). CONCLUSION: DWI is valuable in closed head injury because it identifies additional shearing injuries not visible on T2/FLAIR or T2* sequences. Furthermore, DWI/ADC maps differentiate between lesions with decreased or increased diffusion. DWI is less sensitive than T2* imaging for detecting hemorrhagic lesions.